This invention relates to a machine for the direct soling of shoe uppers, the machine having either a single molding station or a plurality of molding stations aligned adjacent one another. Each such molding station comprises a shoe last holder and at least one shoe last mounted thereon. A shoe upper is fitted on the shoe last, and a die mold has a mold cavity defined together with the shoe last, a mold material inlet passage leading into the mold cavity. An injection mold unit is provided for injecting mold material into the mold cavity through the inlet passage at the heel end of the sole to be molded.
In shoe manufacturing technology, the direct soling of shoe uppers is understood to mean the automatic production of soles while simultaneously mounting the soles on the uppers, sole production preferably being carried out through an injection molding process. The mold material is typically a thermoplastic or rubber.
Machines of this type are generally known as so-called two or four-place machines, i.e., machines having two or four molding stations. Each of these stations has a hopper for containing granular mold material from which the soles are produced. The hopper feeds into an injection molding unit which essentially comprises a worm conveyor, a nozzle and heating means for plasticizing the mold material. The mold which forms a mold cavity together with the shoe last comprises a base die and a pair of side dies which are capable of being laterally separated for opening the mold. The shoe last, together with the shoe upper fitted thereon, is movable downwardly toward the mold. A mold material inlet passage located in the mold dies extends into the mold cavity. And, the shoe last is mounted on a rotatable last holder.
For these known machines, however, each shoe last is typically arranged in such a manner that the heel faces away from the front working end of the machine at which the machine operator is stationed. Thus, the mold material inlet passage likewise faces away from the working end of the machine at an undesireable distance from the operator, thereby making it quite awkward and inconvenient, and even unsafe, for the operator to remove the sprues after each injection molding operation.
And, so-called turntable units have been provided for the direct soling of shoe uppers in which the molding stations are arranged on an annular turntable which is moved past one or more stationary injection mold units. And, the shoe lasts of such machine are arranged in such a manner that the heel cavity into which the injection mold material is fed, is disposed on a side of the machine facing toward the stationary injection mold unit, that is, toward the outside. However, the injection die molds are moved to the separate and stationary injection mold units so that they can be injected directly.